Formation of filaments of artificial silk and the like



R. DE STOUTZ FORMATION OF FILAMENTS OF ARTIFICIAL SILK AND THE LIKEMarch 23, 1937.

Filed Jan. 23, 1936 a W a Y gem-ion 3a 9%; T RNE'YS Patented Mar. 23,1937 PATENT OFFICE. I

FORMATION OF FILAMENTS OF ARTI- FICIAL SILK THE. LIKE Robert de Stoutz,Zurich, Switzerland Application January 23, 1936, Serial No. 60,400

In Switzerland February 2,1935

- 2' Claims. (01. 103-162) In another application for patent of thepresent applicant Ser. No. 719,506, filed April 7, 1934 and allowedOctober 30, 1935, for Pumps, on which has issued Patent No. 2,028,964,there is shown and described an apparatus or mechanical device, designedfor use in the manufacture 'of artificial silk, in which filaments areformed by the extrusion of a cellulose composition through a minuteorifice from the container in which it is heldin a 10 semi-liquid orpasty form, such apparatus comprising a cylinder block within a housing,the cylinder block and the housing being relatively rotatable the-onewith respect to the other and the cylinder block being formed andprovided with a plu- 15 rality of pump cylinders and pistons parallelwith the axis of the cylinder block, a co-operating, stationary workinghead being formed with channels through one of which the cellulosecomposition is drawn from the source of supply into each cylinder inturn and from the other of which the composition is forced to andthrough the orifice of extrusion by the action of each cylinder andpiston in turn. Annular cams are provided for co-operation with thepistons whereby in the rela- 25 tive rotation of the cylinder block andhousing each piston is caused by the action of what may be called thesuction cam, while the corresponding cylinder is in communication withwhat may be called the suction channel, to perform a suction stroke bywhich the cylinder is filled with the composition, and whereby, in thefurther relative movement of the cylinder block and the housing, eachpiston in turn is caused by the action of what may be called thepressure cam to perform a pres- 35 sure stroke by which the compositionin the corresponding cylinder is forced by the pressure stroke of thepiston into the pressure channel and thence to the extrusion orifice.The device or apparatus now to be described and in which the pres- 40ent invention is exemplified embodies the above mentioned elements oftheior'mer' apparatus, with certain improvements'now' to be described.

As filaments produced by the extrusion of a cellulose composition mustbe as nearly uniform 45 as it is possible to make them, it will beappreciated that a very high degree of uniformity in operation must beattained in the apparatus provided, fluctuations of more than one-tenthof 1 per cent in the output not being tolerated. In the 50 developmentof the present invention it has been realized that uniformity of outputdepends on the pressure stroke of the pump and not on the suctionstroke, which can vary within rather wide limits if not less than theproper amount of the compo- 55 sition is taken into each cylinder ateach suction stroke. It is essential, however, to'uniformity in theoutput that the pressure stroke of each piston shall take place withoutaxial clearance, that is, that each piston shall be actuated positivelyand constantly by the pressure cam during the entire pressure stroke.Because of wear on the working parts of the piston operating devicethere would ordinarily be developed some axial clearance which, if notremedied, would entail corresponding delay in the beginning of thepressure stroke of the piston with corresponding irregularity in theoutput.

In the apparatus shown in the application abov mentioned it was soughtto take up such axial clearance by the provision of springs whereby thepiston heads werepressed constantly against the pressure cam. It hasbeen found, however, that the employment of such springs entails thedisadvantage of pressure exerted upon the cooperating members with theresult of increased wear. Moreover, as is always the case when springsare employed, the springs, not being positive in action are notsufiiciently reliable.

In accordance with the present invention the difliculties due to theemployment of springs interposed .at some point between the pressure'camand the pistons are eliminated by the establishment of such operativerelation between the pistons, the suction and pressure channels and thesuction and pressure cams, that each suction stroke of each piston islonger by a surplus amount than the pressure stroke which determines thepump output, the quantity of composition drawn into each cylinder in thesurplus part of the suction stroke being returned into the suction chan-5 ne] of the apparatus before the pressure stroke begins with an initialstroke velocity zero,that is, with a minimum stroke velocity. At thispoint in the operation the surplus composition in the cylinder,- whetherthe quantity be greater or less, 40 having been returned to the sourcethrough the suction channel and a predetermined quantity,

measured by the length 'of the piston pressure stroke remaining in thecylinder, the piston stroke of the piston is effected by the pressurecam,

which then acts upon the piston, and the predetermined quantity ofcomposition is, delivered through the pressure channel, with which thecylinder is then'incommunication, to the extrusion In this manner, ascommunication is orifice. established between the suction channel andeach of the cylinders in succession, a quantity of comnel andthereafter, as the cylinder is placed in communication with the pressurechannel the piston is driven forward by the pressure cam and forces themeasured quantity of the composition through the pressure channel to theextrusion orifice. It will be understood, of course, that the cyindersare so positioned in the cylinder block in relation to each other and tothe suction and pressure channels that, although the delivery of thecomposition from each cylinder begins with the initial velocity zero,the action of the successlve cylinders and pistons, in supplement one toanother, is such that the continuous product of the extrusion orifice isuniform, the volume delivered from each cylinder being dependent solelyupon the pressure stroke of the corresponding piston, and beingindependent of the suction stroke of the piston. It will be observedthat there is at the beginning of the pressure stroke by which theoutput of the pump is determined no clearance between the piston and thepressure cam and that contact (either direct or indirect) between thepressure cam and the piston continues during the entire pressure strokeunder the influence of the friction between the piston and the cylinderand the hydraulic discharge pressure.

In the drawing there is illustrated one convenient and practicalembodiment of the invention, in which the cylinder block rotates withinthe housing and with respect to the working head.

In the drawing- Figure 1 is a view in longitudinal, axial section of anextrusion device or pump constructed in accordance with the invention.

Figure 2 is a face view of the working head, and

Figure 3 is a diagrammatic view illustrating the relations of acylinder, a piston, pressure and suction cams, and suction and pressurechan- In the embodiment of the invention illustrated a suitable housingi is provided with end members 2 and 3, the latter providing a bearingfor the operating shaft 4 and having formed in its plane face 25 arcuatechannels l1 and i8, the channel II, which may be referred to as thesuction channel, being in communication with the source of supply of thecellulose composition through the channel I9, 20 and 2| and the channeli 8, which may be called the pressure channel, being in communicationwith theextrusion orifice, not necessary to be shown, through thechannel 22, 23.

The shaft 4 has at IS a non-rigid driving connection with a cylinderblock 5 whichis thereby -rotated within the housing i. This block isformed with a plurality of cylinders 6 parallel with the axis of thepump.

- At the upper or rear end of the pump there is secured to the endmember 2 a non-rotating annular pressure cam 8, which acts throughinterposed sliding bolts, one of which is shown at 9 in Figure 1,against the heads III of the pistons 'I, one such piston being shown.

It will be understood that as the cylinder block rotates in the housingthe bolts 9, bearing against the annular cam 8, and against the pistonheads iii, are forced forward or downward and the pistons I performtheir pressure strokes.

The suction strokes of the pistons are effected in the rotation of thecylinder block by an annular suction cam I I which, in the constructionshown, acts upon slide bars l3, disposed in longitudinal channels 24formed therefor in the periphery of the cylinder block, each slide barlirbeing formed with 9. lug or nose ,l4 which, through an openingpressure channel ll.

formed therefor in the wall of the corresponding cylinder, engages thehead ll) of the corresponding piston I to effect its return or suctionstroke.

A spring l6, bearing at one end against the driving connection I! and atthe other end through a plate 26 and ball 21 against the cam member 8,

serves to secure proper application of the cylinder block against theplane face 25.

In the rotation of the cylinder block the successive cylinders 6 arebrought alternately into communication with the suction channel I! andthe The fluent composition enters the pump at H, reaches the suctionchannel I! through the channel 20 and 2| and then, on the suction strokeof the piston, is drawn into the cylinders i in succession. At the timeof the pressure stroke of each piston the composition is forced by thepressure stroke of the piston into the channel 22, 23 and thence to theextrusion orifice.

In order that the relation of the several working parts of the pump maybe understood reference may be had to the diagrammatic illustration ofsuch relations in Figure 3 in which successive positions of a piston areindicated at I-VIII; respectively. In this diagrammatic representationthe piston I is shown as bearing directly againstthe pressure cam Bandas provided with a lug or nose I! for direct cooperation with the.suction cam 'I I, the bolts 9 and the slide bars I! being omitted fromthis figure in order to avoid confusion. It may be assumed that alimited amount of axial play, due to wear, has been developed, asindicated at s. It is also understood that the individual'piston underconsideration in the cylinder Bin which it is reciprocated moves fromleft to right, as shown in Figure 3, and in a complete rotation of thecylinder block assumes, under the influence of the suction and thepressure cams, the successive positions indicated at I-VIII,respectively. In the position I the piston is about to begin at normallevel its normal pressure stroke with an initial velocity zero, theconnection of the cylinder with the pressure channel I! just thenbeginning. In the continued relative movement of the cylinder block andcams the piston, acted uponby the rising curve of the cam I, is shown atposition 11 as having completed about half 'of its pressure stroke whichis completed as the piston passestoward position III where it isrepresented as having completed its pressure stroke while the connectionof the cylinder to the pressure channel I8 is about to becut off. Atposition IV the piston is still shown as at the forward limit of thepressure stroke with the connection of the cylinder with the suctionchannel I! about to begin. At position V the piston is shown asbeginning its suction stroke, with the cylinder in full communicationwith the suction channel II. In the continued movement the piston iswithdrawn further than indicated in the position I, the pressure camhaving a drop beyond normal level greater than in the position I and thesuction cam having a greater lift, whereby the piston has a suctionstroke greater than the normal pressure stroke. If the normal pressurestroke is indicated by the double pointed arrow 11 then the completesuction stroke is represented by the doublepointed arrow 0 plus I) minusa and there is thereby drawn into the cylinder a quantity of the liquidcomposition greater than the amount driven from the cylinder inthe-pressure stroke of the piston. In the position VI and also in theposition VII the cylinder is shown as in full communication with thesuction channel l1. Immediately following the extreme drop of thepressure cam and the extreme lift of the suction cam H the pressure camhas a sharp short lift and the suction cam has a corresponding short butsharp drop, whereby the piston is restored in the position VIII to thesame normal level as indicated in the position I and the surplus ofliquid in the cylinder is returned to the suction channel, thecylinder,as it'passes out of communication with the suction channel I'l thenretaining the definite, predetermined measured quantity of liquid, inreadiness to be discharged into the pressure channel as soon as thepiston moves from the position VIII to the initial position I.

As shown in Figure 3 the working faces of the pressure cam 8 and thesuction cam i i are equidistant at all points. If it be assumed that theinitial position of the piston and cylinder is that which it has whenthe surplus composition has been returned to the suction channel, as atthe position VIII, and thepiston is. in readiness for its pressurestroke, it is retained in that position, while the cylinder movesforward from the position VIII, where it passes out of communicationwith the suction channel [17,- to the position I, where it communicateswith the pressure channel i 8. Both cams therefore have a dwell at whatmay be called the normal height, from position VIII to position I. Thencam t has a .iiit of the height represented by the double pointed arrowa and the cam H has a corresponding drop, the pressure stroke of thepiston being thus effected. The lift of cam "i3 is sucseeded-by a dwellwhile the cylinder passes from communication with the pressure channelit to communication with the suction channel it. This dwell is succeededby a drop, in the case of the pressure cam, and a lift, in the case ofthe responding drop of cam in, whereby the piston forces the surpluscharge back into the suction channel Ill and is itself restored to thenormal level, at the positionVIII, in readiness to deliver the measuredcharge into the pressure channei It will be seen that the quantity ofliquid discharged into the pressure. channel by each piston isdetermined exactly by the pressure stroke of the piston which isunvaried in length and that the surplus quantity and only the surplusquantity which is taken into the cylinder during the suction stroke ofthe piston,- whetherjt be larger or smaller, is returned to the suctionchannel;

It will be noted that the maximum drop of the pressure cam and themaximum lift of the suction cam are locatedin such relation to thesuction channel that the charge is completed and the surplus is returnedto the suction channel while the cylinder is in communication with thesuction channel and that the following pressure stroke begins in I withthe initial velocity zero.

The axial clearance s developed by wearcan be increased to the value bwithout affecting the uniformity of the normal pumping operation,

that the length of dwell is not important, it

being evidentthat it might be zero. Furthermore, in a pump having thesine motion without dwell the normal pressure stroke begins at thedeadcenter with the speed zero, while the feed- -ing of the compositioninto the pressure channel begins, because of the overlap, somewhat laterand not atthe zero piston speed.

It willbe understood thateach of the several pistons operates in themanner already described and that the several cylinders and pistons areso placed that the discharge effected by each piston is combined withthe discharge effected by other: pistons, so that there is no variationin the product of the pump at the extrusion orifice.

Wear "of the pistons and cams within the limit above suggested may takeplace without affecting the product of the pump and without the use ofsprings, whereby the pressure of the contacting parts is diminished withcorresponding decrease in wear. All piston movements are eflectedpositively and therefore with the greatest reliability.

The design of the pump can be varied without departing from the spiritof the invention. Thus the cylinder block might be stationary while thecasing, cams and working face are rotated and the cylinders and pistonsmight be arranged radially. I

I claim as my invention:

i. In an apparatus of the character described,

the combination of a working head having a suction channel connected tothe source of supply and a pressure channel, a. cylinder block having aplurality of cylinders and pistons, the working head and the cylinderblock having relative movement the one with respect to the other andeach cylinder being arranged for communication alternately with thesuction channel and the pressure channel, and suction and pressure camsco-operating with the pistons to'eiiect the working strokes of thepistons, the normal pressure stroke of each piston for delivery to thepressure channel beginning at normal level with a minimum pressurestroke velocity and the suction cam having a maximum lift and thepressure cam maximum drop beyond said normal level while the cylindersare in communication with the suction channel.

2. In an apparatus of the character described, the combination of aworkingrheadhaving a suction channel connected to the source of sup plyand a pressure channel, a cylinder block having a plurality of cylindersand pistons, the working head and the cylinder block having relativemovement-the one with respect to the other and each cylinder beingarranged for communication alternately with the suction channel and thepressure channel, and suction and pressure cams cooperating with the'pistons to effect the working strokes of the pistons, the working facesof the cams being equidistant and having a dwell at normal level, thedelivery stroke of each piston to they pressure channel beginning atnormal level with a minimum piston stroke velocity, a. succeeding liftof the pressure cam and suction cam beyond said normal level. and asucceeding lift of the pressure cam and corresponding drop of thesuction cm to the normal level while the cylinders are in communicationwith the suction channel.

ROBERT DI B'I OUTZ.

